Ball stud

ABSTRACT

A ball pivot ( 3 ) of a ball and socket joint for a motor vehicle, with a pivot ( 2 ) and with a joint ball ( 1 ) connected thereto. A recess ( 12 ) with a magnet ( 13 ) arranged therein is provided in the ball pivot ( 13 ). An intermediate space ( 17 ), which is filled with a nonmagnetic material ( 16 ) for fixing the magnet ( 13 ), is formed between the jacket surface ( 14 ) of the magnet ( 13 ) and the inner wall ( 15 ) of the recess ( 12 ).

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a United States National Phase application ofInternational Application PCT/DE 2004/001867 filed Aug. 23, 2004 andclaims the benefit of priority under 35 U.S.C. § 119 of GermanApplication DE 103 41 466.5 filed Sep. 5, 2003, the entire contents ofwhich are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention pertains to a ball pivot of a ball and socketjoint for a motor vehicle, with a pivot and with a joint ball connectedto same, wherein a recess with a magnet arranged therein is provided inthe ball pivot. The present invention pertains, furthermore, to a balland socket joint with such a ball pivot.

BACKGROUND OF THE INVENTION

A ball and socket joint for a motor vehicle, in which a ball head isinserted into a ball socket, is known from EP 0 617 260 A1. A permanentmagnet, opposite to which a magnetic field-sensitive sensor is locatedin the area of the ball socket, is arranged in the ball head.

A ball and socket joint for a motor vehicle, in which a ball pin havinga pin section and a ball section is accommodated rotatably and pivotablywith its ball section in a calotte shell-shaped mount in a housingsection, is known from DE 101 10 738 C1. A permanent magnet, opposite towhich a sensor element having two Hall sensor plates is located, isarranged in the ball section.

The arrangement of the magnet in the ball pivot is not describedsufficiently in the above-mentioned documents, so that drawbacks mayarise especially in the manufacturing process. Thermal shock stressesmay also lead to problems in case of insufficient fastening of themagnet in the ball pivot. Furthermore, ball pivots for motor vehiclesare regularly manufactured from a ferromagnetic material, which mayadversely affect the shape of the magnetic field generated by the magnetconcerning a measurement of this magnetic field. It is possible, inparticular, that the magnetic flux takes place decisively in theferromagnetic material and it is not ensured that “sufficient field” isavailable to the magnetic field-sensitive sensor.

SUMMARY OF THE INVENTION

Based on this state of the art, the basic object of the presentinvention is to provide a ball pivot, which is suitable for massproduction and in which a magnet is securely mounted. Furthermore, anadverse effect of the magnetic field generated by the magnet concerningmeasurement of that magnetic field by means of a magneticfield-sensitive sensor shall be avoided even if a ferromagnetic materialis used for the ball pivot.

According to the invention, a ball pivot of a ball and socket joint isprovided for a motor vehicle, with a pivot and a joint ball, which isconnected to the pivot. A recess with a magnet arranged therein isprovided in the ball pivot. An intermediate space, which is filled witha nonmagnetic material to fix the magnet, is formed between the jacketsurface of the magnet and the inner wall of the recess.

According to another aspect of the invention, a ball and socket joint isprovided for a motor vehicle, with a ball and socket joint housing andwith a ball pivot, which is mounted therein rotatably and pivotably andhas a pivot and a joint ball connected thereto. A recess with a magnetarranged therein is provided. An intermediate space, which is filledwith a nonmagnetic material for fixing the magnet, is formed between thejacket surface of the magnet and the inner wall of the recess.

The ball pivot according to the present invention for a ball and socketjoint for a motor vehicle has a pivot and a joint ball connectedtherewith, wherein a recess with a magnet arranged therein is providedin the ball pivot. An intermediate space, which is filled with anonmagnetic material for fixing the magnet, is formed between the jacketsurface of the magnet and the inner wall of the recess.

The solution according to the present invention may also be to provide aplurality of recesses or magnets, and it is also possible, for example,to arrange a plurality of magnets in one recess.

Due to the fact that the intermediate space formed between the jacketsurface of the magnet and the inner wall of the recess is filled with anonmagnetic material, the magnet, designed especially as a permanentmagnet, can be mounted in the ball pivot in a reliable process withinthe framework of mass production. Furthermore, the adverse effect on themagnetic field generated by the milagnet concerning a measurement ofthis magnetic field by means of a magnetic field-sensitive sensor, whichis arranged especially outside the ball pivot, is reduced by thearrangement of the nonmagnetic material around the magnet in theintermediate space especially if the ball pivot is made of aferromagnetic material. The shape of the magnetic field generated by thenonmagnetic material, which shape is more favorable for the magneticfield measurement, makes possible the more reliable and more accuratedetermination of the position of the magnet by means of this magneticfield measurement. It is also possible to compensate differences in thethermal expansion characteristics of the magnet and the ball pivot incase of thermal shock stresses by suitably selecting the nonmagneticmaterial.

The magnet may be arranged in the recess such that there is no directcontact between the magnet and the ball pivot. However, the magnet ispreferably in direct contact with the ball pivot by one of its frontsides, so that the mounting of the magnet in the ball pivot can becarried out in a simpler manner. The magnet is now pushed, for example,into the recess until its front surface facing the ball pivot comes intocontact with the bottom surface of the recess. The mounting of themagnet is thus self-adjusting with respect to the longitudinal axis ofthe recess. Furthermore, tilting of the magnet is extensively ruled out.Such a tilting could lead to errors in the determination of the positionof the magnet by a magnetic field measurement. Furthermore, the magneticfield will have a more favorable course for the magnetic fieldmeasurement due to the contact if the ball pivot is manufactured from aferromagnetic material.

The ball pivot or the joint ball may be made of a ferromagneticmaterial, preferably a ferromagnetic steel, in the area of the recess,but also as a whole; for example, spring bronze, aluminum or plastic,such as polyamide (PA) or polyoxymethylene (POM) have proved to besuitable nonmagnetic materials. However, the different coefficients ofthermal expansion, whose effects are not negligible in a temperaturerange of −40° C. to 120° C., are to be borne in mind in selecting thematerials. Furthermore, there is a risk of water absorption in case ofplastics. Some material characteristics, which can be taken into accountin the manufacture of the ball pivot according to the present invention,are presented below: Coefficient of thermal expansion of steel: 0.0000161/° C. (1/K) Coefficient of thermal expansion of aluminum: 0.0000238 1/°C. (1/K) Coefficient of thermal expansion of plastic PA: 0.175⁻⁴ 1/° C.(1/K) Coefficient of thermal expansion of POM: 1.1⁻⁴ 1/° C. (1/K)Moisture absorption of PA: 1.7 % Moisture absorption of POM: 0.8 % Waterabsorption of PA: 0.2 % Water absorption of POM: 5.5 %The values for polyamide are obtained, e.g., for PA66.

The magnet may have a cylindrical or truncated cone shape, and acylindrical shape of the recess proved to be advantageous. Inparticular, the internal diameter of the recess is greater than themaximum external diameter of the magnet.

In case of a truncated cone shape of the magnet, especially the smallerfront surface of the magnet faces away from the ball pivot. This shapeof the magnet affects the magnetic field of the magnet, so that “more”field is available for a magnetic field-sensitive sensor for detectingthe magnetic field. The reason for this is the relatively higher energycontent compared to a cylindrical magnet of equal magnetic field exitarea, which energy content is coupled with the volume of the magnet.Thus, a small magnetic field exit area is created by the truncated coneshape in case of a large magnet volume.

Mounting can be facilitated by a ring receiving the magnet being formedfrom the nonmagnetic material, which ring can be bonded in the recesstogether with the magnet. This ring is preferably made of aluminum or aplastic and forms especially a separate component.

Furthermore, self-centering of the ring becomes possible in the recessby the adhesive, and the use of a partially elastic adhesive alsoguarantees reliable connection for the case in which strong thermalshock stresses develop. Such an adhesive can compensate the differencesin the coefficients of thermal expansion of the ring and the ball pivot.For example, a UV-curing adhesive can be used as an adhesive if the ringis made of a material that is transparent to UV light. If the ring ismade of plastic, the ring may also be injection molded directly into therecess having the magnet according to an alternative.

However, the magnet may also be completely embedded in plastic, in whichcase this plastic is molded on the magnet especially by injectionmolding. The body formed by the magnet and the plastic is especially aseparate component and can be bonded and/or pressed in the recess. AUV-curing adhesive can be used in this case as well. As an alternative,the plastic may, however, also be injection molded into the recesshaving the magnet.

According to another variant of the present invention, the magneticmaterial may be in the form of a stamped and bent part, into which themagnet is inserted. The stamped and bent part, preferably made of metal,is made especially of spring bronze and can be pressed into the recesstogether with the magnet. Furthermore, it is possible to make thestamped and bent part partly elastic, so that it will be elasticallysupported against the inner wall of the recess in the mounted state. Themagnet itself may also be pressed into the stamped and bent part, inwhich case the magnet is held in the stamped and bent part in anon-positive manner.

The stamped and bent part preferably has a ring-shaped design and hastwo concentric legs and a web connecting these to one another. It isthus possible to arrange the magnet within the inner leg, the outer legbeing designed as a spring being supported against the inner wall of therecess. Because of the pretension of this spring and the surfaceroughness of the inner wall of the recess in the ball pivot, thearrangement formed by the stamped and bent part and the magnet is heldin the ball pivot in a non-positive manner. It is also possible to embedthe inner or outer leg in a plastic sleeve, in which the magnet may bearranged as well.

The outer leg may be divided by free spaces into a plurality of springtongues, which are arranged around the inner leg and are supportedagainst the inner wall of the recess to form the non-positive connectionwith a spring force. The free spaces may also extend into the web.

The object of the present invention is accomplished, furthermore, by aball and socket joint for a motor vehicle, with a ball and socket jointhousing and a ball pivot, which has a pivot and a joint ball connectedthereto and is mounted rotatably and pivotably in the ball and socketjoint housing, in which ball pivot a recess is provided with a magnetarranged therein. An intermediate space, which is filled with anonmagnetic material to fix the magnet, is formed between the jacketsurface of the magnet and the inner wall of the recess.

The ball pivot of the ball and socket joint according to the presentinvention may be varied in the same manner as the ball pivot accordingto the present invention.

The present invention will be described below on the basis of preferredembodiments with reference to the drawings. The various features ofnovelty which characterize the invention are pointed out withparticularity in the claims annexed to and forming a part of thisdisclosure. For a better understanding of the invention, its operatingadvantages and specific objects attained by its uses, reference is madeto the accompanying drawings and descriptive matter in which a preferredembodiment of the invention is illustrated.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a sectional view of an embodiment of a ball and socket jointaccording to the present invention;

FIG. 2 is a schematic sectional view of a first embodiment of the ballpivot according to the present invention;

FIG. 3 is a schematic sectional view of a second embodiment of the ballpivot according to the present invention;

FIG. 4 is a schematic sectional view of a third embodiment of the ballpivot according to the present invention;

FIG. 5 is a schematic sectional view of a fourth embodiment of the ballpivot according to the present invention;

FIG. 6 is a top view of the embodiment according to FIG. 5;

FIG. 7 is a schematic sectional view of a fifth embodiment of the ballpivot according to the present invention;

FIG. 8 is a top view of the embodiment according to FIG. 7;

FIG. 9 is a schematic sectional view of a ball pivot according to thepresent invention before the mounting of the magnet and of thenonmagnetic material;

FIG. 10 is a schematic sectional view of the ball pivot according toFIG. 9, with the magnet inserted but without nonmagnetic material; and

FIG. 11 is a schematic sectional view of the ball pivot according toFIG. 1 before the mounting of the magnet and of the nonmagneticmaterial.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the drawings in particular, FIG. 1 shows a sectional viewof an embodiment of the ball pivot according to the present invention,in which a ball pivot 3 provided with a joint ball 1 and with a pivot 2is mounted rotatably and pivotably in an interior space 4 of a ball andsocket joint housing 5 through the intermediary of a bearing shell 6.The ball pivot 3 extends with its pivot 2 through an opening 7 from theball and socket joint housing 5 and is provided with a thread 8 at itsend facing away from the ball 1. In the area of the ball and socketjoint housing 5 facing away from the pivot 2, the ball and socket jointhousing has a mounting opening 7a, which is closed with a cover 9, onthe surface of which that faces the joint ball 1 a magneticfield-sensitive sensor 10 is arranged.

With its area facing the cover 9, the joint ball 1 is provided with aflattened area 11, in which a cylindrical recess 12 is formed, intowhich a permanent magnet 13 is inserted. The recess 12 and the permanentmagnet 13 extend into the interior of the joint ball 1, and anintermediate space 17 filled with a nonmagnetic material 16 is formedbetween the jacket surface 14 of the magnet 13 and the inner wall 15 ofthe recess 12. The magnet 13 is in contact with the bottom surface 19 ofthe recess 12 by its front surface facing the ball pivot 3 and is fixedin the recess 12 via the nonmagnetic material 16. As is apparent fromthe figure, the magnet 13 with its front side 20 facing away from theball pivot 3 projects slightly from the flattened area 11. Forprotection against environmental effects, the ball and socket joint isprovided in the usual manner with a sealing bellows 21, which is fixedon the ball and socket joint housing 5 by means of straining rings 22and is sealingly in contact by a sealing area 23 with the pivot 2.

Even though the magnet 13 is arranged in the area of the joint ball 1that faces away from the pivot 2 according to FIG. 1, it is alsopossible to provide the magnet 13 in another area of the ball pivot 3.

FIG. 2 shows a first embodiment of the ball pivot 3 according to thepresent invention, in which a ring 24 made of plastic is bonded togetherwith a magnet 13 into a recess 12 of the ball pivot 3 and the magnet 13is in contact by its front side 18 facing the ball pivot 3 with thebottom surface 19 of the recess 12. The plastic used is transparent toUV light, and the adhesive cures on exposure to UV light, which isespecially favorable for mass use. There is no gap between the ring 24and the pivot 3, so that a possible focus of corrosion is ruled out.

FIG. 3 shows a second embodiment of the ball pivot 3 according to thepresent invention, in which a cylindrical magnet 13 is completelyembedded in a plastic element 25 manufactured according to the injectionmolding method. The body formed by the magnet 13 and the plastic element25 is pressed into a recess 12 of the ball pivot 3, and the magnet 13 isin contact with the bottom surface 19 of the recess 12 by its front side18 facing the ball pivot 3, so that, on the whole, a robust component iscreated in a simple mounting process. Because of the pressing in, theuse of an adhesive can be eliminated, so that no dripping and dryingtimes of a UV-curing adhesive need to the taken into account.

FIG. 4 shows a third embodiment of the ball pivot 3 according to thepresent invention, in which a truncated cone-shaped magnet 13 iscompletely embedded in a plastic element 25 manufactured according tothe injection molding method. The magnet 13 is in contact with thebottom surface 19 of the recess 12 by its front side 18 facing the ballpivot 3 and tapers from the bottom surface 19 with increasing distancefrom the latter.

FIG. 5 shows a fourth embodiment of the ball pivot 3 according to thepresent invention, in which a cylindrical magnet 13 is pressed into astamped and bent part 26 made of spring bronze. The stamped and bentpart 26 is of a ring-shaped design and has two concentric legs 27 and28, which are connected to one another via a web 29. The inner leg 27extends in parallel to the jacket surface 14 of the magnet 13 and isfirmly in contact with same, so that the magnet 13 is held in thestamped and bent part 26 in a non-positive manner. The end of the innerleg 27 facing the ball pivot 3 is joined by the ring-shaped web 29 andpasses over into the outer leg 28, which extends along the inner wall 15of a recess 12 provided in the ball pivot 3 and is elastically incontact with this inner wall 15. The stamped and bent part 26 thus hasan approximately U-shaped cross section, and the body formed by thestamped and bent part 26 and the magnet 13 is held in the recess 12 in anon-positive manner because of the spring force of the outer leg 28 andthe surface roughness of the inner wall 15 and is secured againstfalling out. Furthermore, the magnet 13 with its front side 18 facingthe ball pivot 3 is in contact with the bottom surface 19 of the recess12. This embodiment has few parts of a simple design, which can bemounted easily, and the area of the recess 12 that is open toward theoutside and is not used can be additionally used as a grease reservoirif the ball pivot 3 is used for a ball and socket joint, into thehousing interior space of which a lubricating grease is introduced. Atop view of the embodiment according to FIG. 5 is shown in FIG. 6, whichshows that the outer leg 28 as well as part of the web 29 areinterrupted by free spaces 29 a around the inner leg 27. A plurality ofspring tongues 28 a, which are elastically supported against the innerwall 15 of the recess 12, are thus formed around the inner leg 27.

FIG. 7 shows a fifth embodiment of the ball pivot 3 according to thepresent invention, in which, just as in the fourth embodiment, a stampedand bent part 26 is provided to fix a cylindrical magnet 13 in a recess12 of the ball pivot 3. The stamped and bent part 26 manufactured fromspring bronze has a ring-shaped design and has two concentric legs 27and 28, which are connected to one another via a web 29. Unlike in thepreceding embodiment, the inner leg 27 of the stamped and bent part 26is surrounded with a plastic sleeve 30, which is manufactured from aplastic by injection molding. The inner leg 27 is located completelywithin the wall 31 of the plastic sleeve 30, in the interior space ofwhich the magnet 13 is arranged. The ring-shaped web 29 joins at the endof the inner leg 27 that faces the ball pivot 3 and passes over into theouter leg 28, which extends along the inner wall 15 of the recess 12provided in the ball pivot 3 and is elastically in contact with thisinner wall 15. The stamped and bent part 26 thus has an approximatelyU-shaped cross section, and the body formed from the stamped and bentpart 27, the plastic sleeve 30 and the magnet 13 is held in the recess12 in a non-positive manner and is secured against falling out becauseof the spring force of the outer leg 28 and the surface roughness of theinner wall 15. To secure the magnet 13 against falling out, the plasticsleeve 30 is closed on its front side facing away from the ball pivot 3by a cover 32, which is made in one piece with the plastic sleeve 30 andis manufactured simultaneously with this [sleeve] from a plasticaccording to an injection molding method. The embodiment can be mountedespecially easily, and the space of the recess 12, which is open towardthe outside, can be used as a grease reservoir, as in the precedingembodiment. Furthermore, the magnet 13 is protected from damage by theplastic sleeve 30, which is closed on one side. A top view of theembodiment visible in FIG. 7 is shown in FIG. 8, which shows that theouter leg 28 as well as parts of the web 29 are interrupted by freespaces 29 a around the inner leg 27. A plurality of spring tongues 28 a,which are elastically supported against the inner wall 15 of the recess12, are thus formed around the inner leg 27 or the plastic sleeve 30.

FIG. 9 shows the ball pivot 3 shown in FIGS. 2 through 8 in the crudestate, and FIG. 10 shows the ball pivot 3 with a cylindrical magnet 13but without nonmagnetic material. The magnet 13 is inserted into arecess 12 formed in the ball pivot 3 such that its front surface 18facing the ball pivot 3 is in contact with the bottom surface 19 of therecess 12 and is arranged centrally in the recess 12, so that aring-shaped intermediate space 17 is formed around the magnet 13 betweenthe jacket surface 14 of the magnet and the inner wall 15 of the recess12 for accommodating the nonmagnetic material.

According to an alternative process of manufacturing the ball pivot 3according to the present invention, both the ball pivot 3 and the magnet13 may be held by a bracket of an injection mold, which bracket is notshown, wherein a plastic, which is used as the nonmagnetic material, isinjected into the intermediate space 17 according to the injectionmolding method. It is possible to manufacture in this manner, forexample, an embodiment that is similar to that shown in FIG. 2 but thering 24 is formed by directly injecting the plastic into theintermediate space 17. Secure connection is achieved hereby between themagnet 13 and the pivot 3, and crevice corrosion is not possible becauseof the absence of gaps, Furthermore, close tolerance of the position ispossible, because the ball pivot 3 and the magnet 13 can be insertedinto the injection mold at predetermined locations.

The transition area between the joint ball and the pivot is not shown inFIGS. 2 through 11 for the sake of clarity. The ball pivots 3 shown inFIGS. 2 through 10 also have no flattened area around the recess 12.Yet, the embodiments shown in FIGS. 2 through 10 may also be embodiedwith the ball pivot 3 shown in FIG. 11 with the flattened area 11, whichball pivot is shown in this figure in the crude state.

The same reference numbers are used for the same or similar features inall embodiments. While specific embodiments of the invention have beenshown and described in detail to illustrate the application of theprinciples of the invention, it will be understood that the inventionmay be embodied otherwise without departing from such principles.

1. A ball pivot of a ball and socket joint for a motor vehicle, the ballpivot comprising: a pivot; a joint ball connected to said pivot; amagnet having a jacket surface, the ball pivot having a recess with saidmagnet arranged therein, an intermediate space, which is filled with anonmagnetic material to fix said magnet, is formed between said jacketsurface of said magnet and an inner wall of said recess.
 2. A ball pivotin accordance with claim 1, wherein said magnet has front sides and isdirectly in contact by one of said front sides with said ball pivot. 3.A ball pivot in accordance with claim 1, wherein said magnet iscylindrical or truncated cone-shaped.
 4. A ball pivot in accordance withclaim 1, wherein said recess is cylindrical.
 5. A ball pivot inaccordance with claim 1, wherein said magnet is arranged in a ring madeof a nonmagnetic material.
 6. A ball pivot in accordance with claim 5,wherein said ring is bonded in said recess together with said magnet. 7.A ball pivot in accordance with claim 1, wherein said magnet is embeddedin plastic.
 8. A ball pivot in accordance with claim 7, wherein theplastic is injected onto said magnet by injection molding.
 9. A ballpivot in accordance with claim 7, wherein a body formed by said magnetand said plastic is pressed into said recess.
 10. A ball pivot inaccordance with claim 9, wherein said body formed by said magnet andsaid plastic is bonded in said recess.
 11. A ball pivot in accordancewith claim 1, wherein said magnet is inserted into a stamped and bentpart made of a nonmagnetic material.
 12. A ball pivot in accordance withclaim 11, wherein said stamped and bent part consists of spring bronze.13. A ball pivot in accordance with claim 11, wherein said stamped andbent part is pressed together with said magnet into said recess.
 14. Aball pivot in accordance with claim 13, wherein said stamped and bentpart is elastically supported against said inner wall of said recess.15. A ball pivot in accordance with claim 11, wherein said magnet ispressed into said stamped and bent part.
 16. A ball pivot in accordancewith claim 11, wherein said stamped and bent part has a ring-shapeddesign and has two concentric legs and a web connecting these to oneanother.
 17. A ball pivot in accordance with claim 16, wherein saidinner leg is embedded in a plastic sleeve.
 18. A ball pivot inaccordance with claim 17, wherein said magnet is arranged in saidplastic sleeve.
 19. A ball pivot in accordance with claim 1, whereinsaid ball pivot consists of a ferromagnetic material, especially aferromagnetic steel, at least in the area of said recess.
 20. A ballpivot in accordance with claim 19, wherein the ball pivot consistsentirely of a ferromagnetic material.
 21. A ball and socket joint for amotor vehicle, the ball and socket joint comprising: a ball and socketjoint housing; a ball pivot, which is mounted rotatably and pivotably insaid housing and has a pivot and a joint ball connected thereto, saidball pivot having a recess; and a magnet arranged in said recess,wherein an intermediate space, which is filled with a nonmagneticmaterial for fixing said magnet, is formed between a jacket surface ofsaid magnet and an inner wall of said recess.